Eraser



Aprilrzz 1924. f 1,491,720

' G. C. MUIRHEAD ERASER Filed April 5. 1923 IN VEN T OR ,0 6. GMU/MEAD i a a@ l M M d ATTORNEYS Mmmm WITNESSES Patented Apr. 22, 1924.

i AUNITED s'refrrzs` PATENT OFFICE.

1GEORGE C. MUIB/HEAD, 0F WORI'AND, WYOMING.

f ,Ennsna applicati@ mea Aprii 5, i923. serial No. 630,150.

To all whom 'it may concern:

Be it known that I, GEORGE C. MUIRHEAD, a citizen of the United States of America, and a resident of Worland, in the county of Washakie and State of Wyoming,lhave invented a new and Improved Eraser, of which the following isa description.

My inventionrelates to erasers and more particularly to an eraser employingva rotary erasing blade and a clamp presentingjaws adaptedA to permitv rotation of the blade for bringing a new edge portion thereof into a given positionnfor use or to hold the plate against turning after a given adjustment of the blade.

` The invention particularly relates to an eraser in which the blade and clamp are so related that. the blade pro-jectsa gradually increasing distance beyond the adjacent clamp edges. e f

Y AThe generaly object ofvmy invention is to' provide Va novel clamp means so `formed and so Aassociated ywith thesteel orlike cuttingY blade that the maximum edge portion of the blade is made available for erasing and thegraduallv increasing projection of the blade Vis continued for more than a Y half circle of the cutting edge.-

i thereof Figure 2 1s a central longitudinal section Figure 3 is an end elevation on an enlarged scale of the edge portion of the clamp and eraser with a fragment of paper exaggregated to show the mode of functioning of the burnishinghclamp edges in an erasing operation; Y

Figure 4 is a side elevation of the eraser showing a slightly modified form of clamp. Referring at first more particularlyV to Y YFigures 1 and 2 the form of the invention shown in said iigures includes a round eraser blade 10 advantageously formed of steel and made with a keen cutting edge. The blade is heid in a holder in' the form of a clamp j 11 made of a length of flat metal doubled on itself. and embraced vby a slidable' band 12. The-sides of the clamp 11 tend to-vs'ep'arate slightly but upon moving the 'slide 12 to a forward position the sides rmly clamp the blade 10 in position. The front' terminal portions of the sides of the clamp 11 form jaws 15. On one jaw 15 is a lateral stud 13 adapted to project through a central pin hole in the blade 10 and into a registering hole 14 inthe opposite side of; Y

the clamp 11. Y

The relative form and arrangement of the jaws l'andblade'lOis such that saidblade projects an increasing distance beyond the end edges of the clamp 11 from one side j of said yclamp to the other. In Figure 1 the pivot pin 13 of the blade 10 is eccentrically positioned in the clamp while thefpn hole in the blade 10 is central so that there is an eccentric relation between the rounded jaws and said blade. v The end edges of thejaws 15 are in the true arc of a circle. In order to obtain the maximum available cutting edge on the blade 10 beyond vthe clamp jaws 15, I continue the curvature of thevend edges beyond the halr` circle, that is to say, rearward of the axis of the pin 13`and said rounded end edgesY of the jaws form a curvilinear angle with the body of the clamp 11.. Adjacent the angle 16 theA minimum projection of theblade 11is attained, the degree of projection increasing about the end of the jaws toward angle 1 at the opposite side. The described forma- Y tion not `only gives the maximum available cutting edge on the blade 10 but it promotes eiiciency in erasing at dierent angles, and is'particularly effective in erasing from paper yon the platen roller of a. type writing machine.

In Figure the described clamp band 12 andv the sameeraser blade 10 are provided as well as the the clamp 111 providedwith 1700,

pin 113 corresponding with vthe pin-13 Vand the pin hole 114 corresponding with the hole 14C. Also, the end edges of the jaws 115 yare rounded and form curvilinear angles at 116, 117 with the clamp-111. Thev clamp jaws 115, however, instead of having edges A rounded in the true arc of a circle are spiral oron a curve the radius of which increases from one angle 117 toward the angle 116 at the opposite side, thereby obtaining the effect of the arrangement in.` Figures 1 tot! of producing a maximum available cutting edge on the blade 10 while preserving the characteristic that at one side the blade projects to the minimum extent, and preserving the curvilinear angle 116 having in view erasures to be made in a paper' on' a platen roller for example.` j

The use of the round steel Yeraser is thus made practical and eicient to the highest degree. It will he readily understood that by sliding the clamp band 12 rearwardly to dotted line position in Figure 1 permits the blade tobe adjusted should it become dull at one portion, the turning of the blade about its'own axis serving to bring the cutting edge from beneath the clamp sides to a position or'use. VThe `described arrangement permits also the ready removal and vrenewal of the blade.

From Figure 3 it will be seen that the edges 18 of the clamp jaws 15 constitute burnishers at the sides of the cutting blade 10. The burnishing edge functions at thatLV side of the jaws ywhereV the blade' projects to a slight extent. rlhus, the paper A indicated conventionally in Figure 3 may'have an erasure made therein as shown exaggerated at @and it will be seen that as the blade slightly scrapes and penetrates the paper, either or both burnishing edges may be caused to smooth and polish the paper following the cutting action of the eraser blade. The increasing projection of the blade beyond the clamp edges maires possible a selectivityA in the depthof the guarded blade. `I would state in conclusion that while the illustrated examples constitute practical embodiments of my invention, I do'not limit myself Vstrictly' to the rexact details herein illustrated, since, manifestly,.the same can be considerably varied without departure from the spirit of the invention as defined in the appended claims. Y Having thus described my claim: y 1. An eraser comprising a round steel blade formed with a cutting edge, and Va holder formed with clamp jaws having pivot means on which said blade is centrally mounted and presenting curved edges at the front, said blade projecting beyond said front edges ofthe jaws to an increasing extent from thevedge portion at one side of the pivot means toward the opposite side of said means.

2. An eraser comprising a round eraser element, and a holder formed with clamp jaws having pivot means on which said eraser element is centrally mounted and.

invention,

Vpresenting curved edges at the front, said elementprojecting beyond said front edges of thev jaws to ank increasing extent Vfrom the edge portion at one side of the pivot means toward the opposite side of said means.

Meije@ 3. VAn eraser comprising around eraser element', and 'a holder formed with clamp jaws having pivot means on which said eraser 4element vis centrally mounted and presentingcurved edges at the front, said element projecting beyond said front edges of the jaws to an increasing extent trom the edge portion'at one side of the pivot meansv toward the opposite side of saidV means, said curved edges of the jaws forming anglesV with the side edges of.v the body of n'the holder. Y f

'41. An 'eraser comprising a round eraser v element, and a holder.V formed with clampjaws having pivot means on which said eraser element is centrally mounted and presenting curvededges at the front, said element projecting beyond said front edges of the. jawsto an increasing extent from theV i 'projecting to a gradually increasing; extent toward'the opposite side. l .Y

6. An eraser comprising a round eraser blade, and a holder` formed with clamp jaws accommodating said blade therebetween,

said jaws having roundededges to constitute burnishing means in association with the blade. Y

7. An eraser comprising an eraser blade presenting a rounded cuttingedge, and a holder therefor, VVsaid holder comprising a j member at a side/of the blade and beyond which the blade projects to a varying degree, said member having a rounded'burnishing edge. Y

8. An eraser comprising an eraser blade,

and a holder formed with clamp jawsfor Vsaid blade, the edges of said jaws being rounded and disposed inward from the cutting edge of the blade a distance for. said rounded edges tov constitute burnishers for burnishing and smoothing the paperin association with the cuttingy action of the blade. f

9. An eraser comprising a roundferaser element, and a holder formed with clamp jaws between which said element VisV turnably mounted, the end edges of Athe jaws being curved and the curvature continuing rearward of the'pivot means, said element projecting beyond the jaws to the minimumV extent at one side edge of the said jaws and projecting to a gradually increasing extent toward the opposite side, said curved edges of the jaws forming anangle with the side edges of the body of the holder.

l0. An eraser comprising a round eraser element, and a holder formed with clamp jaws accommodating said element therebetween, means to bind the jaws in clamping relation on said element, and pivot means eocentrically positioned with respect to the jaws and on which means said eraser element is centrally mounted, said eraser element projecting beyond the end edges of the jaws to an increasing extent from a point at one side edge and rearward of the pivot means. toward the opposite side of the pivot means.

1l. An eraser comprising a round steel blade formed Wah a cutting edge, and a holder presenting clamp jaws and having a pivot on which said blade is centrally mounted, the end edges of the jaws presenting a curve of increasing radius from one side edge to theropposite side edge and terminating at points rearward of' the pivot Y v pin, said curved'edges of the jaws forming curvilinear angles with the side edges of the body of the holder, and means to tighten the jaws on the blade or to permit turningv movement of the blade, said blade projecting beyond the end edges of the jaws to an increasing extent YVfrom the curvilinear angle at one side edge of the holder toward theV opposite side. GEORGE C. MURHEAD. 

